public class UnicodeResultSetMetaData implements ResultSetMetaData {

...

private static List<Integer> UNICODE_EQUIVALENT = List.of(Types.VARCHAR, Types.LONGVARCHAR);

private static List<String> UNICODE_EQUIVALENT_NAMES = List.of("VARCHAR",
		"CHARACTER VARYING",
		"LONGVARCHAR",
		"VARCHAR2",
		"VARCHAR_CASESENSITIVE");

public int getColumnType(int column) throws SQLException {
	int type = meta.getColumnType(column);
	if (UNICODE_EQUIVALENT.contains(type)) {
		return Types.NVARCHAR;
	} else {
		return type;
	}
}

public String getColumnTypeName(int column) throws SQLException {
	String type = meta.getColumnTypeName(column);
	if (UNICODE_EQUIVALENT_NAMES.contains(type)) {
		return "NVARCHAR";
	} else {
		return type;
	}
}